Prostate brachytherapy postimplant dosimetry: a comparison of suture-embedded and loose seed implants.

Objective: To compare postimplant dosimetry and seed embolization rates for prostate brachytherapy implants using suture-embedded and loose seeds.

Methods: Dosimetric analysis of the whole prostate, prostate quadrants, rectum, and surrogate urethra was performed on 54 loose seed and 81 RAPIDStrand (RS) patients. Seed embolization rates were determined from chest radiographs.

Results: Whole prostate V100 and D90 did not differ significantly for the loose seed (V100 = 90.5%, D90 =153.2 Gy) and RS groups (V100 = 91.5%, D90 = 151.6 Gy) (p = 0.43 and 0.65, respectively), but V150, V200, and contiguous V200 were higher (p < or = 0.003) for the RS group (59.9%, 28.3%, and 23.2%, respectively) than the loose seed group (52.5%, 22.8%, and 16.1%, respectively). Extraprostatic measures (conformity index and external index) were also different at the p < 0.05 level. The embolization rate was 40% in the loose seed group and 14% in the RS group.

Conclusions: The most significant difference between the two study groups was a decrease in the embolization rate. Although some statistically significant changes in postimplant dosimetry were observed, they were nevertheless small.